"You go," I said. "I will remain here. We should keep a careful watch on this house." "You are right," he replied. "I shall not be gone long." * * * * * After Ero Shan's departure I commenced another careful investigation of the premises. Once again I went through every room searching for some secret place where a person might be hidden. I had covered the upper stories of the house thus, and was searching the first floor. The dust of neglect lay heavy upon everything, but I noticed that in one of the back rooms it had been disturbed upon the floor at a point where Ero Shan and I had not walked. Previously this had escaped my notice. It seemed to me that it might be fraught with importance. I examined the floor carefully. I saw footprints. They approached a wall; and there they stopped; there seemed to be a path worn in the dust to this point in the wall. I examined the wall. It was covered with a form of synthetic wood common in Havatoo, and when I rapped upon it it sounded hollow. The wall covering was applied in panels about three feet wide, and at the top of the panel I was examining was a small round hole about an inch in diameter. Inserting a fore-finger in this hole I discovered just what I had imagined I would discover--a latch. I tripped it; and with a slight pressure the panel swung toward me, revealing a dark aperture beyond it. At my feet I dimly discerned the top of a flight of steps. I listened intently; no sound came up to me from the gloom into which the stairs disappeared. Naturally, I was convinced that Nalte's abductor had carried her down that stairway. I should have waited for the return of Ero Shan, but I thought that Nalte might be in danger. I could not think of wasting a single precious instant in delay. I placed a foot upon the stairs and started to descend; and as I did so the panel closed softly behind me, actuated by a spring. I heard the latch click. I was now in utter darkness. I had to feel my way. At any moment I might come upon Nalte's abductor waiting to dispatch me. It was a most uncomfortable sensation, I can assure you. The stairway, which was apparently cut from the living limestone that underlies Havatoo, ran straight down to a great depth. From the bottom of the stairway I felt my way along a narrow corridor. Occasionally I stopped and listened. At first I heard not a sound; the silence was the silence of the grave. Presently the walls commenced to feel moist; and then, occasionally, a drop of water fell upon my head. Now a low, muffled sound like the shadow of a roar seemed to fill the subterranean corridor like a vague, oppressive menace. On and on I groped my way. I could not advance rapidly, for I was compelled to feel every forward footstep before taking it; I could not know what lay beyond the last.